For the general dilution ventilation system to work, there must be at least 20 room air changes per hour. The fan which supplies air to this area produces 1,500 cubic feet per minute (cfm) (Q).

In order for the local exhaust ventilation system to remove the contaminant to acceptable concentrations, the capture velocity must be at least 140 feet per minute (fpm). The proposed local exhaust system ventilation system uses a 1.0 feet diameter duct and a fan that provides a total volume of 1,275 cubic feet per minute (cfm). The source of the contamination is located 1.5 feet from the opening of the duct. Determine the appropriate ventilation control and calculate the capture velocity. showing the equations for both dilution ventilation system and utilizing an exhaust hood system.